A life limiting factor in the design of nickel cadmium batteries has been the life of the separators utilized in the fabrication of the batteries. The nickel-cadmium spacecraft batteries utilize aqueous potassium hydroxide (KOH) solutions as the electrolyte, and operate under electrolyte starved conditions. State-of-the-art nickel-cadmium batteries contain separators fabricated from either a nylon or polypropylene felt that has been treated with a wetting agent. These separators are life limited because of the chemical instability of nylon and the chemical instability of the polypropylene wetting agent in the battery electrolyte.
In particular polypropylene battery separators, because of the intrinsic non-wettability of the material, tend to cause battery failures because of separator dry outs and low electrolyte retention. Attempts to solve this problem by adding wetting agents to the polypropylene separators have been unsuccessful because of the instability of the wetting agents when exposed to aqueous potassium hydroxide solutions.
It is therefore an objective of the invention disclosed herein to provide an improved separator for use in alkaline storage batteries; an additional objective of the invention disclosed herein is to provide a novel means for increasing the wettability of polypropylene and other intrinsically nonwettable chemically inert materials designed to be used as separators for storage batteries; and a still further objective of this invention is to provide an inexpensive stable porous organic separator for use in alkaline storage batteries.